The present invention relates to a technology for performing high-speed, automatic inspection of the appearance of industrial products. More specifically, the present invention relates to a system for inspecting fine circuit patterns on an electronic circuit substrate and an inspection method thereof.
Japanese laid-open patent publication number Hei 2-170279 discloses an example of a conventional pattern inspection system. In this type of conventional inspection system, a line image sensor (linear image sensor) is used to detect circuit patterns, and defects are detected by performing image processing on the detected image data using dedicated circuitry such as alignment circuits and image differential detection circuits.
In this conventional inspection sensor, the process of finding defects from an image detected with a line image sensor is performed with hardware through dedicated electronic circuitry. This can be done at very high speeds since hardware processing is used. On the other hand, the need for designing and producing dedicated electronic circuitry also means slower development and high development costs. Furthermore, if the algorithm used to detect defects is improved, making the corresponding changes to the circuit substrates is difficult.
The object of the present invention is to implement an inspection system that reduces the development time and development costs for inspection systems and that allows the evaluation processing algorithm to be changed easily.
In order to achieve the object described above, the present invention uses a PC equipped with an image input feature to capture images detected by a line image sensor. The detected images are transferred to a plurality of PCs connected by a local area network (LAN), and defects are detected through software processing on the plurality of PCs. Using general-purpose PCs for this provides the following advantages.
Since individual PCs are inexpensive, using multiple units will still be less expensive than designing and producing dedicating electronic circuitry, and development time can be reduced as well. Since processing is done in software, there is a high degree of flexibility and changes in algorithms can be implemented easily. Furthermore, even for other inspections that perform different types of evaluation processing, the same system architecture can be used, and only the software needs to be changed. Also, since there has been very rapid improvements in PCs, inspections can be made faster by replacing the PCs with the newest models.
The system according to present invention is not restricted to the use of PCs for the capturing/transfer of detected images and detecting of defects. Other small-scale computers can also be used such as workstations and servers.
These and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.